If Europeans thought a drought was something that happened only in Africa, they know better now. After four years of below?normal rainfall (in some cases only 10 percent of the annual average), vast areas of France, Spain, Portugal, Belgium, Britain and Ireland are dry and barren .Water is so low in the canals of northern France that waterway traffic is forbidden except on weekends.Oyster growers in Britain report a 30 percent drop in production because of the loss of fresh water in local rivers necessary for oyster breeding.In southeastern England, the rolling green hills of Kent have turned so brown that officials have been weighing plans to pipe in water from wales.In Portugal,farmers in the southern Alentejo region have held prayer meetings for rain-so far,in vain.
上段中第二句是主题句,它点明了全段的中心思想,即:四年来,法国、西班牙、葡萄牙、比利时,英国及爱尔兰的降雨量低于常年,这些国家的广大地区都严重缺水。下面的各句都是围绕这一主题展开的。
从上面两段中我们可以看到英语的段落只能有一个中心思想,如要再论述其他与该段中心思想无关的内容应另起一段。